Livestock Products
Senior 2 · Agriculture
Livestock Products
Lesson 3 of 4
22 min
Let's begin
When a cow or a pig is slaughtered, much more than meat is produced. There is the hide or skin, which can become shoes and bags; fat, which becomes lard; blood and bones, which become animal feed and fertiliser. Many Rwandan hides are sold raw at a low price, and too many are spoiled by knife cuts or rot before they reach a tannery.
In this lesson you will learn how to preserve beef and pork, how to process pig products and by-products, and how to keep hides and skins in good condition.
Preservation cannot rescue meat that is dirty or diseased. Animals should be slaughtered in an approved slaughterhouse (abattoir), where a veterinary inspector checks the animal before slaughter and the carcass after it. Meat should be kept off the floor, away from flies, and chilled as soon as possible.
| Method | How it is done | Why it works |
|---|---|---|
| Chilling | Carcass kept in a cold room at about 0–4 °C | Slows microbes and enzymes; keeps meat for days |
| Freezing | Meat kept at −18 °C or colder | Stops microbial growth; keeps meat for months |
| Drying | Thin strips of lean meat, often salted, dried in air and sun or over low heat | Removes the water microbes need |
| Salting and curing | Meat rubbed with salt, or soaked in brine; curing salt may contain nitrite | Salt draws water out of microbes by osmosis; nitrite also kills bacteria and gives cured meat its pink colour |
| Smoking | Meat hung in smoke from a slow, smouldering wood fire | Dries the surface; chemicals in smoke slow microbes |
| Canning | Meat sealed in airtight cans and heated to a high temperature | Heat kills microbes; the sealed can keeps new ones out |
Fresh lean beef is about three-quarters water. A butcher dries 10 kg of beef strips until they weigh 40% of their fresh weight.
The dried meat is lighter and easier to transport, and it keeps for weeks if stored dry.
| Product | What it is |
|---|---|
| Pork | Fresh pig meat, preserved by chilling or freezing. |
| Ham | The hind leg of the pig, cured with salt (and often smoked). |
| Bacon | Cured, often smoked, meat from the back or belly. |
| Sausages | Minced meat mixed with salt and spices, filled into casings (cleaned intestines or artificial casings), then cooked, smoked or chilled. Salt makes the proteins bind the meat together. |
| Lard | Pig fat melted (rendered) and strained; used for cooking, keeps well when cool and covered. |
| By-products | Skin (leather), bristles (brushes), blood and bones (dried to make blood meal and bone meal for feed and fertiliser), manure (compost and biogas). |
Food safety: pork must always be cooked thoroughly. Undercooked pork can carry the cysts of the pork tapeworm, which can cause serious disease in people.
A recipe for ham uses curing salt at 3% of the meat's mass. How much salt is needed for a 12 kg ham?
Salt = 3% × 12 kg = 0.03 × 12 = 0.36 kg = 360 g.
In the leather trade, a hide is the skin of a large animal such as a cow, and a skin is from a small animal such as a goat, sheep or pig. A raw hide starts to rot within hours in warm weather, so it must be preserved ("cured") before it goes to a tannery, where it is turned into leather.
Tip
Memory hook: "Hides are Huge, skins are Small." And for drying hides, "frame, shade, air, never ground and sun".
Exam technique: if a question asks for pig by-products, do not list pork, ham and bacon: those are products. By-products are skin, bristles, blood, bones and manure.
Distinguish between a hide and a skin, giving one example of each.
Solution: A hide comes from a large animal (a cow's hide); a skin comes from a small animal (a goat's or sheep's skin).
Explain why a hide should be dried on a frame in the shade and not on the ground in the sun.
Solution: On a frame in the shade, air reaches both sides so the hide dries evenly without rotting underneath. On the ground the lower side stays wet and rots, and hot sun overheats and cracks the hide, lowering the leather's quality.
20 kg of fresh meat is dried until it weighs 35% of its fresh weight. What is its dried mass?
Solution: 0.35 × 20 = 7 kg.
List three by-products obtained when pigs are slaughtered, and one use of each.
Solution: Any three, for example: bristles for brushes; blood dried into blood meal for feed; bones ground into bone meal for feed or fertiliser; skin for leather; manure for compost or biogas.
Why must pork always be cooked thoroughly?
Solution: Undercooked pork can contain the cysts of the pork tapeworm, which infect people. Thorough cooking kills them.
Summary
Sources and credits
The Rwandan examples, worked examples and practice questions are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
